Voltage Drop Calculator

Calculate voltage drop with kVA mode, temperature correction, automatic cable sizing, and metric/AWG support.

System Type

Input Mode

Supply Voltage (V)

Load Current (A)

Cable Length (One Way)

Conductor Temperature (°C)

Wire Size System

Wire Size

Calculated Current: 20.00 A

Voltage Drop: 6.50 V

Voltage Drop: 1.62%

Voltage at Load: 393.50 V

Recommended Minimum Cable Size (≤3% drop): 53.5 mm² (equivalent AWG area)

Voltage Drop Calculator – Accurate Electrical Load Analysis

Voltage drop occurs when electrical current flows through a conductor and loses voltage due to resistance. Excessive voltage drop can cause poor equipment performance, overheating, and energy inefficiency. This Voltage Drop Calculator helps electricians, engineers, and installers determine voltage drop for DC, single-phase AC, and three-phase AC systems with professional-level accuracy.

Why Voltage Drop Matters

Electrical standards such as NEC recommend keeping voltage drop below 3% for branch circuits and 5% total for feeders and branch circuits combined. High voltage drop may lead to:

Reduced motor efficiency
Lighting dimming or flickering
Overheating conductors
Increased power losses
Equipment malfunction

This calculator automatically checks compliance and suggests proper cable sizing when voltage drop exceeds safe limits.

Voltage Drop Formulas Used

For DC and Single-Phase AC:

V_drop = 2 × I × R × L

For Three-Phase AC:

V_drop = √3 × I × R × L

Where:

I = Current (Amps)
R = Conductor resistance per unit length
L = One-way cable length

If power is entered in kVA instead of current, the calculator uses:

I = (kVA × 1000) / (V × √3 × PF) (Three-phase)

Temperature correction is applied using:

R_T = R_20°C × (1 + α × (T − 20))

Essential Features Included

Supports DC, Single-Phase, and Three-Phase systems
Current input or kVA input mode
Power factor adjustment for AC systems
Temperature correction factor
AWG and Metric (mm²) wire sizes
Automatic cable size recommendation
NEC 3% voltage drop warning indicator

Typical Conductor Data Reference

Wire Size	Area (mm²)	Material	Typical Max Current (A)
14 AWG	2.08	Copper	15 A
10 AWG	5.26	Copper	30 A
6 AWG	13.3	Copper	55 A
16 mm²	16	Aluminum	65 A

How to Use This Voltage Drop Calculator

Select system type (DC, Single-phase, or Three-phase).
Choose input mode (Current or kVA).
Enter supply voltage and cable length.
Select conductor material and wire size system.
Enter operating temperature if different from 20°C.
Review voltage drop result and recommended cable size.

The calculator instantly displays voltage drop in volts, percentage drop, final load voltage, and recommended minimum cable size to maintain safe operation.

Professional Applications

This tool is suitable for residential installations, commercial electrical design, solar system planning, industrial motor circuits, and distribution panel calculations. By combining temperature correction, kVA conversion, and automatic cable sizing, it ensures accurate and reliable voltage drop analysis for real-world applications.

Use this calculator to optimize conductor selection, improve energy efficiency, and maintain electrical system reliability in compliance with industry standards.